Thermodynamically stable colloid dispersion electrolytes with the Tyndall effect for practical zinc-ion pouch cells

Abstract

In aqueous zinc (Zn) metal secondary batteries, some interfacial side reactions, such as the hydrogen evolution reaction (HER), anode corrosion and dendrite growth, often lead to short circuit and cycling performance deterioration. Here we select four kinds of amino acid monomers (i.e., lysine, glutamate, cysteine and phenylalanine) with different polarity side chain groups to tailor pentapeptides, successfully constructing a thermodynamically stable colloid dispersion electrolyte system with the Tyndall effect for Zn metal secondary batteries. The proposed electrolyte system composed of the tailored lysine pentapeptide (LP) effectively suppresses Zn dendrite growth through regulating the (002) crystalline plane orientation. Furthermore, the LP has strong attraction towards H₂O molecules, thereby achieving desolvation of Zn²⁺ ions and reducing anode corrosion as well as the HER. In this LP-based colloid dispersion electrolyte, the Zn//Zn symmetric cell demonstrated an unprecedented ultralong cycling time beyond 10 000 hours (416 days) at 2 mA cm⁻². The developed Zn-ion pouch cells with a high cathode mass loading of ∼ 28.7 mg cm⁻² displayed a capacity retention of ∼83.7% after 1000 cycles at 0.5 A g⁻¹, which is superior to most recently reported zinc-ion pouch cells. The proposed thermodynamically stable colloid dispersion electrolyte is a new aqueous electrolyte system for economical, safe and long-lifespan Zn metal secondary batteries.